Composite piston



C. R. SHORT Oct. 29, 1929.

COMPOSITE PISTON File Feb. 25, 1926 atroz man Viet. 29, l-@Z F DAYTON, OHIO,l ASSIGNOR TO GENERAL 'MOTORS RESV MICHIGAN, A CORPORATION 0F DELAWARE CHARLES n. snonr,

conronarron, or DETROIT,

COMPOSITE PISTON Application filed February 23, 1926. Serial No. 90,161.

Thisinvention relates to pistons for internal combustion engines and particularly to the type of piston which has a thin walled Skirt preferably of steel, or other equally '5 strong material, and a head of material of relatively high heat conductivity such as aluminum.

The object of the invention is to reduce the cost of the manufacture of a piston of the type referred to and this aim of the invention is accomplished by a novel construction an method of manufacture.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a side view partly in vertical 1ongitudinal section of a piston constructed in accordance with the present invention.

Fig. 2 is a side viewlooking in the 'direction of arrow 2 0f.Fig. 1.

Fig. 3 is a sectional view of line 3--3 of Fig. 1.

Fig. 4 is a plan view of one of the parts used in the construction of the piston; and

Fig. 5 is a section on line 5 of Fig. 2.

The process of manufacture about to be described consists in the main in providing a cast metal body, which includes the piston head, two piston pin bosses integral with the head and sheet metal bodies which are attached to the bosses in the process of casting, and in providing a thin walled tubular skirt, which is adapted to be readily attached to the sheet metal bodies projecting from the bosses by process of riveting, or spot welding.

One of the sheet metal bodies, which are to be anchored to the piston pin bosses, is represented by the Fig. 4, which shows a flat plate 20 provided with a central opening 21, having a notched periphery and with smaller holes 22 near opposite edges ofplate4 20. The aper' ture 21 is shaped so that it will embrace the material of the piston pin bosses.` Two of the plates 20 are placed in a suitable mould so that they are parallel and the apertures 21 arel in alignment. The-mould is shaped so that by 59 a casting process there will be provided a cast diametrically opposite piston pin bosses 32 by bridging members 33. The plates 20 will be securely anchored to the bosses 32, and side portions thereof, which are provided with holes 22, will project beyond the sides of the bosses 32. The bosses 32 may be cast with apertures `34the walls of which may be afterwards machined to receive a piston pin.

There is provided a cylindrical, thin walled metal skirt 40, preferably of steel and having adjacent its lower edge an inwardly extending flange 41 and two diametrically opposite apertures 42, which are slightly larger than aperture 34 of the bosses 32. Near each of its apertures 42 the skirtf4() is punched to provide four U shaped openings 43, which dene four tongues 44. wardly away from the circular contour of the skirt, as shown in Fig. 3 in order to provide a suitable means for attaching the skirt to the plates 20. The apertures in the tongues 44 are located so that they will be in alignment with the holes 22 in the plates 20 when the skirt and piston head are assembled, as

the plates 20 by rivets 45, which pass through the holes into plates 2O and the tongues 44. The plates and tongues may be joined also by spot welding.

In this manner there is provided a piston of relatively light weight having a head of relatively high heat conductivity and therefore not susceptible to the development of hot spots, and having a relatively rigid thin such a manner that there will be substantially no distortion of the skirt due to the difference in expansion between the metal of the should expand faster than the skirt, thereby relative to the skirt, the ears 44 and the portion of plates 20, which project beyond the bosses 32, will yield sufficiently to accommodate the relative movement referred to withouttransferring stress to the walls of the skirt, which would cause it to deviate from a true cylindrical form,

metal structure which includes la piston head 30 having its cylindrical side wall joined to shown in Fig. 3. rI he skirt 40 is attached to walled skirt which is joined to the head in l skirt and the metal of the head. If the head tending to produce movement of the bosses 32 j i plates being provided Whilethe forms of embodiment of the invention as herein disclosed, constitute a preferred lform, it is to be understood that other Aforms might be adopted, all coming Within the scope of the claims which follow.

What is claimed is as follows l. A piston comprising an integral head and piston pin boss structure, a cylindrical, A

relatively thin-Walled skirt of a metal different-from sai'd structure and provided with tongues formed from portions of the skirt which are bent inwardly from the cylindrical wall of the skirt, and relatively thinplates having their intermediate portions secured respectively to the bosses and secured near their edges to the tongues of the skirt.

2. A piston comprising an integral head and piston pin bosses, a cylindrical skirt structure Within which said bosses are positioned, said skirt structure being provided with inwardly extending tongues, and relatively thin plates connecting said bosses to said skirt, the plates having their central portions secured to the bosses and their edge portions secured to said tongues.

3'. Structure as set forth in claim 2, the with central apertures and the bosses being cast in engagement with the edges of said apertures.

4. Structure as set forth in claim 2, the tongues and plates being flexible to permit of yielding under distortion due to unequal expansion of the head and skirt.

5. A piston comprising a head and piston pin bosses rigidly connected thereto, a sheet metal skirt having tongues formed thereon, a pair of plates of relatively thin flexible material arranged substantially parallel to each other, said plates having their central portions rigidly secured respectively to said bosses and their edge portions secured to said tongues. y

6. A piston having a cast metalbody comprising integral head and piston pin bosses and a skirt of sheet metal, said skirt provided With portions bent inwardly from the contour of the skirt to constitute attaching means, and a plurality of plates connecting said body and skirt, each plate having a central portion secured to said body and end portions secured to said attaching means.

In testimony whereof I atix my signature.

CHARLES R. SHORT. 

